https://www.cnn.com/2019/12/30/us/magnifying-glass-christmas-gift-lawn-fire-trnd/index.html
This kid has a promising future in Optics.
The parents “thought [the magnifying glass] was for reading”???
Seriously?
Were they ever 12 years old?
How did they not realize that it was going to be used to set paper on fire? And maybe ants. In Texas, fire ants.
By the way, only in Texas would the logical outcome of this be that the lawn was set on fire!
I loved the beginning of the video when the one young boy said, “Not me.” 
When I was in high school, my physics teacher sent us outside on a nice sunny day with a bunch of lenses and instructions to experiment with finding their focal lengths. And so we did. One of these lenses was a good 12 inches in diameter, and was able to quickly start dry grass on fire. And so we did. The resulting fire very nearly got out of control, burning a couple hundred square feet of the schoolyard before we were able to stamp it out.
In grad school I worked with a rather powerful laser: 20 watts of output (a typical laser pointer is usually no more than a few milliwatts of output). The beam was about an inch in diameter coming out of the laser head, and one day I took a large lens and focused that beam down to a point. I soon discovered that you could pass a sheet of paper across the narrowest waist of that beam and cut it completely through. Great fun.
Moral of the story:
Being 12 years old is not any kind of requirement for engaging in mayhem with light and fire.
Sounds like you had real genius. Did you ever try making popcorn with it?
Nope. And despite my best efforts, I still can’t hammer a six-inch spike through a board with my penis, either.
I almost did start a proper fire with it (the laser, not my penis). When I first started working with it, the beam was firing across the lab and landed on a cardboard box. No optics involved, so the beam was at its full width, but it was still pretty intense. For reference, sunlight is about 0.1 watts per square centimeter, and this beam was almost 4 watts per square centimeter. My advisor was with me at the time, and he was the first to wonder whether that cardboard box was going to light on fire. After maybe 30 seconds, we finally did notice that the box was indeed starting to let out a disconcerting amount of smoke. That was the day I learned about beam dumps.
When I was in grad school I was working with a dye laser pumped by an argon ion laser*. As usual when working on it, I had the cover off. The argon ion laser beam was focused to a small spot at the waist of the dye laser in order to efficiently pump the dye laser. A small portion of the beam wasn’t absorbed and passed through the dye jet, but by that time it was expanding and, I though, pretty harmless (as long as I didn’t try to look right into it).
Boy, was I wrong.
I was wearing a black polyester T-shirt as I stood in front of this. After a couple of minutes, my stomach felt warm. I looked down to see that the expanded, depleted argon laser beam had melted a hole in my shirt the exact size and shape of the beam.
Moral: don’t wear black plastic synthetic shirts while working with lasers.
Many years later , at the small company I was working at, someone left a small, milliwatt HeNe laser on when he went to lunch. It was being blocked, ultimately, by the white sheetrock wall, so there was, he thought, nothing to worry about. Little did he know that he was in the company of jokers. Someone else drilled a perfect hole in the wall where the beam hit, then stuck a match in the hole and lit the head. The flaring match made a wonderful burn mark around the drilled hole. He extracted the burnt match and awaited results. Individual #1 returned from lunch, saw the burn mark where his little HeNe laser was pointed, and promptly freaked out.
*The dye laser, in turn, pumped a color center laser. This, in turn, excited the impurity centers that I was really interested in. Starting with a 20 kW argon laser we lost power at each stage of the process, with microwatts of fluorescence coming out of my impurity centers.
I thought the usual pre-adolescent magnifying glass trick was burning ants and caterpillars. And little sisters.
Where I grew up this wouldn’t even have been news. Happened all the time. Like, what if we climbed up on the roof, do you think we could set the leaves in the gutter on fire?
Yep.
Could we ignite a newspaper, sitting on the passenger seat of a locked car on a sunny day?
Yep.
Of course we burned our names into any pieces of wood we could find. That didn’t always go perfectly as planned, either.
We didn’t even need magnifying glasses if we had a friend who wore glasses.
Santa Claus: “Whaddaya want something like that for, kid? You’ll set somebody’s lawn on fire!” boot to the face
Eyeglasses will only work if they’re for someone farsighted. Glasses for the much more common nearsightedness will spread out the beam, not bring it to a point.
And Cal, of course the joker was “someone”. Someone who happened to work at the same place as you. And you just happened to know all of the details of the prank that that “someone” pulled.
CalMeacham finds himself at wrong end of laser beam, gets ventilated. (Tom Tomorrow cartoon depicting the event.)
Honestly and For Real, it wasn’t me. But I was there and watched.
Regarding the eyeglasses, as many people responding to the problem of using the myopic “Piggy’s” eyeglasses to start a fire in Lord of the Flies have pointed out, you can turn those negative lenses into positive lenses that will focus light to a point if you hold them horizontally and fill them with water.
I intend to use this trick if I ever find myself stranded on a deserted island with a bunch of pre-adolescents who don’t act like the ones in Verne’s Deux ans de vacances, or Ballantyne’s The Coral Island. Or if I’m teleported back to Imperial Rome.
To be fair, the kid told his dad first:
Where the heck did you live where setting fire to somebody’s car wasn’t news? (I certainly hope there’s more to the story, because an ignited newspaper in a car seems to me like it would soon spread to the entire interior of the car being on fire.)
Yeah, me and my neighborhood buddies went through a phase between about 8 and 10 where the coolest thing we could conceive of was burning stuff with magnifying glasses of various kinds. Ants, pillbugs (they pop), newspapers, pine bark, pine cones, leaves, twigs, etc…
The absolute best was the 6" diameter lens off my friend’s dad’s old desk magnifier- we took off the springloaded arm and went to town, setting someone else’s newspaper completely aflame one fine summer day.
Well…as soon as it started to smolder, we left. We were terrible kids, actually. We were essentially an unsupervised gang. Or maybe a mob.
My cousin (also part of this gang) was the one who set his roof on fire. This was great, the fire department actually had to come out and put the fire out. Old wood shingles plus leaves in gutter plus magnifying glass. It did not make the news. He did get sent to military school. Not for that, but eventually. He kind of escalated.
It may be a gender divide. I happened to watch this news item with my mother and found she was unaware that a magnifying glass could be used to start fires.
The news articles say that Nissa-Lynn Parson thought the magnifying glass was for reading but Justin Parson knew what was happening.
Amateurs. Go find yourself a big-screen rear-projection TV and do some foundry work.
About a year ago I had an 8-inch diameter parabolic telescope mirror aluminized. When I got it back, before I mounted it in the telescope, I of course had to see what would happen to various objects put at its focal point while it was pointed at the sun. Let me tell you, an optically perfect parabolic mirror beats any magnifying glass. I could set a piece of paper ablaze in about one second.